The objectives of the program are as follows. In onchocerciasis, we intend to examine the immunologic responses of patients exhibiting well-categorized clinical manifestations of the disease, both before and after chemotherapy, in order to characterize the immune events which contribute to the development of lesions and their exacervation by anthelmintic intervention. We propose to relate these findings to field observations on the biology and epidemioloogy of O. volvulus infection in an intensely endemic region of tropical territory in Sudan. The longer term goal is to establish a basis for improved medical management of infected persons at the individual patient and population levels, and to place this system in a developing strategy for treatment and control of the disease. In Schistosomiasis our objective is to evaluate the pharmacologic and toxicologic consequences of treatment with proven antischistosomal agents, with a view toward construction of an optimal chemotherapeutic strategy best suited to the treatment and control of the infection in Southwestern Sudan. This depends heavily on the characterization of host-parasite-vector-interactions within the study zone, both for the identification and selection of clinical cases and for the development and testing of hypotheses on prevention and control measures. In malaria our objective is to examine the extent to which immunologic factors in host blood influence procedures for the detection of chloroquine sensitivity. Field isolates will later be analyzed antigenically and accumulated data on drug sensitivity/antigenic type will be used to examine the epidemiologic patterns of P. falciparum oorganisms in the Sudan, particularly as they relate to patterns emerging in other parts of Africa and the tropical world.